Frederick h



. a land7-pier.-

top and bottom of opposite iron columns B B are stilfened by tension-rods d, connecting opor may not, have the tension-rods; they have FREDERIGKH. sMITH, or

`NITETJ STATES NT ci; rrcn.

BALTIMORE, MARYLAND.

IMPROVED BRIDGE.

Specification forming part of Letters Patent No. 89,94ES, dated May 11, 1869.

To all whom it may concern:

` Be it` known that 1,FREDERIOK H. SMITH, ofthe city of Baltimore, and county of f Baltimore, and State of Maryland, have invented a new and useful Improvement in Bridges, bf which the following is a full and clear description, reference being had to the accompanying drawings making part of this specification.

-The nature of my improvement in bridges y consists in the construction and arrangement of a substructure composed of iron piers, secured to each 4other in a specified manner. The system of piers being a unit, the superstructure connected with it maybe removed and replaced Without lessening the rigidity or strength of the substructure.

Figure l is an elevation of the vbridge having my improvements connected therewith. Fig. 2 is a transverse elevation of acl1anv new-pier. Fig. 3 is atransverse elevation'of A A are foundationpiers, of masonry; their cap-stones, a, are located immediately above high-Water mark in the channel-piers those upon the land sides are of only suflicient height to insure a stable structure. There are two foundationpedestals to each pier. The columns B B are rmly secured together at the top and bottom, and intermediate points, by struts and diagonal tie-rods and braces b b. Lateral diagonal bracing-rods c connect the in the channel-piers, and the iron columns B B posite ends of the same columnsB or B', these tension-rods being strutted apart at their centers by struts e. The land-piers may,

the strut f connecting their middle points, and the lateral diagonal bracing-rods g, one pair above and the other pair below, and extending from the strut-bar f. In the short end piers E one pair of lateral diagonal bracing-rods is employed. Each iron pier is connected with, the neighboring one by diagonal rods or chords h, which extend from the top of one pier to the bottom of the other ones. From the joints of the channel-piers rods or struts k extend to and connect with the landpiers or masonry, or other irm foundation. These lon gitudinal rods or struts stiien the piers at `the joints, or other points necessary to prevent ilexure, and thereby replacing the up-and down tension-rods where short spa-ns are used. The superstructure F is secured upon the top of the piers. It may be in sections extending from pier to pier, and rmly secured to them, or a continued truss system, as convenience or exi gency requires. DThe ordinary masonry pier is itself' so extremely heavy as to require 'extraordinary precautions and expenditures to secure suitable foundations, where the circumstances are atall difficult, and the prostration of the pier is the frequent result of miscalculations, or an unlocked-for failure in foundation or shaft materials.

The great cost of good masonry, coupled with the fact of the necessity of foundations where rock bottom is not attainable, is the most prominent reason why railroadcompanies decline to accept the necessities involved, and are constantly erecting cheap wooden trestlin g, tem- Yporary crib-work piers, or making use of other questionable and dangerous expediente. To design a system of iron piers that shall completely obviate the well-known difficulties attending the use of masonry piers, and, at the same time, have no defects of its own, and be adapted to all situations and conditions, with the least possible expense, has long been arecognized object of study with engineers and others, and many structures," more orless creditable to their designers, have been erected. From four to twelve columns have generally been used in each pier; these .columns inclining toward each other from all directions, from bottom to top, the vertical height being divided into stories by struts, braces, and ties, the height of the story being fixed by economical length of column as used. The masonry foundations for these piers are cruciform, square, oblong, or diamond-shape, but in all, they cover more square feet of foundationwork than the masonry pier, as the inclination yof thecolumns is greater than the batter of Ythe masonry. The weight to be sustained by these piers is divided out among the columns, and as the stories are necessarily proportioned in height to the diameter ofthe columns used, it follows that the number of the stories increases as the diameter of the column decreases, thereby causing surplus materia-itc 2 ede/is be used in the increased quantity of strutting., bracing, and ties, as well as increased workmanship, and insecurity from defective joints.

In the improved plan submitted, `the meta-l is concentrated in two columns in each pier, thereby seeurin g the greatest diameter of column with its consequent increased strength per square inch of section, and diminution of strutting and other stiffening-work. These two columns are connected with each other by cross-struts and tie-rods, the intermediate struts being omitted where spans of super-` chored to the masonry, or other firm object near the end of the structure, and passing thence from one pier to another through the joints, and thence to a similar iirm anchorage near the other end of the structure, unless long spans should intervene, in which case they stop by an attachment to the long-span piers. In order to keep these rods or struts straight, they may be supported at proper intervals by su spenders from above; and in order to counteract the effect of temperature changes, washers of rubber or other elastic medium may be interposed between the columns and nuts on the rods or strut ends. It is, however, not believed that any injurious strain can be brought to bear upon these rods or struts, since the extension produced by a rise of one hundred degrees is only equal to that resulting from a good working strain. The piers are connected one with another by rods attached to the top, and running each way to the feet of other piers, thereby giving much greater stiffness and freedom from longitudinal motion, under the action of moving loads, than in the case of the independent pier, relying only upon its own base. These longitudinal stays also tend to support any column in position until repairs can be made, in case any masonry pedestal should settle or get knocked out. All these rods, are under the control of screw adjustments, so that the bridge can be fully loaded in hot Weather, and everything secured to a full bearing.

Wire or wire rope, or other materials, can be used instead of iron rods. The superstructure can be of any desired material, span, or system of trusses, either connected together from end to end of bridge, or unconnected, as maybe pre ferred, the piers being thoroughly anchored and self-supporting in all directions.

It is believed that this system gives the most rigid, and, therefore, the most durable, as well as the lightest, and, therefore, the most economical structure, to perform the required dnty, that has yet been designed.

What I claim as new, and desire to secure by Letters Patent is,-

s 1. Anchoring the tops of iron or steel piers of bridges by means of longitudinal diagonal stays, or equivalent tension'members, to the feet or pedestals of other piers or abutment's, substantially as herein described, so that the pier can be formed of but two columns, or equivalent compression members, and still have the great longitudinal base afforded by the spread of the longitudinal diagonal stays, to give it stability under the action of temper ature or moving load. y

2. In combination with the system of longitudinal diagonal stays specilied in the preceding clause, I claim iron or steel piers, stiff- Acned by means of up-and-down strut or tension-rods and cross-strut or tension-rods, at such point in the height of the pier as will prevent iiexure, substantially as shown and described.

3.' Stift'euing iron or steel bridge-piers bj means of longitudinal rods or struts anchored to or abutting against masonry, and connecting therewith the piers, and the piers yvith other piers, at such point in their heights as will prevent iiexure, substantially as described. 4. The combination of theiron or steel piers of bridges with thelongitudinal diagonal stays, the up-and-down stiii'ening system, and the longitudinal stiffening system, substantially as and for the purposes set forth.

FREDERICK H. SMITH.

Witnesses:

C. L. FISHER, W. J. NORTON. 

